Ecoinformatics Portal Bayreuth
(2015-2017)
Vegetation plots and vegetation-plot databases
Vegetation plots records (relevés) are descriptions of plant community composition of defined small areas of typically 1-1000 m² in size in a standardised way. On these areas, all occurring plant species (vascular plants, but often also bryophytes, lichens and algae) are recorded, together with an importance value (e.g. % cover or cover-abundance classes of Braun-Blanquet). Additionally, they contain information on the structure of the vegetation (cover and height in total and of individual layers), location, time and in most of the cases at least some environmental factors measured or estimated in the plot (e.g. slope and aspect, relief position, land use type, soil parameters).
Vegetation plot records are used in one way or another in most plant community ecological research. They have been sampled all around the world in a relatively uniform manner since about 100 years. This results in estimated 5-10 million existing relevés in Europe (with its strong phytosociological tradition) and perhaps 10-20 million worldwide. Such vegetation-plots have big advantages for macroecological studies of plants and vegetation over more widely used data sources such as the Global Biodiversity Information Facility (GBIF) that provides point distribution data for individual species:
- they provide true community data of species co-occurring in close neighbourhood and sharing the same environmental conditions and competing for the same resources,
- they provide information on dominance and frequency of each species,
- they contain information on true absences (i.e. a species not listed for a plot does not occur there, which is not the case with GBIF data), an important feature for modelling studies, and
- they typically contain at least some structural and environmental parameters determined locally (while GBIF studies have to rely exclusively on modelled environmental parameters at much coarser scale)
Additionally, the distribution data of individual species that is contained in plot data, if mobilised would enormously expand the data content of GBIF. Still the construction of large vegetation-plot data lagged behind that of GBIF and other species-based data mainly because of the significantly more complex data structure. However, first sizeable national and regional vegetation-plot databases emerged since the late 1990s, first in the United Kingdom, followed by the Netherlands, the federal state of Mecklenburg-Vorpommern in Germany and the Czech Republic. The Global Index of Vegetation-Plot Databases (GIVD), launched in 2010, provide for the first time a global metadatabase of existing vegetation-plot databases. When the problems of unifying many different taxonomic concepts of national databases, as well as their varying database structures, large supranational databases finally emerged during the last few years, the European Vegetation Archive (EVA) in 2012 and the global vegetation-plot database “sPlot” in 2014. It is evident that with more than 1 million vegetation plots each and a good spatial coverage, both integrated databases will open a new era of plant community ecology, macroecology and biogeography. A whole series of first analyses is on the way, some of them already published.
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